San Luis Obispo County weather to get cooler, maybe wetter

The North County baked under high temperatures over 100 degrees last weekend, but a major cool down started Monday, and some computer-model forecasts are even hinting at the possibility of rain next week.

“We are seeing some real changes in our weather pattern,” said John Lindsey, a Pacific Gas and Electric Co. meteorologist at Diablo Canyon nuclear power plant. “There is a lot of storm activity in the Gulf of Alaska, and fronts are coming down the West Coast.”

A cool weather system will reach San Luis Obispo County today, bringing with it the chance for morning drizzle and fog, then afternoon highs in the 70s in San Luis Obispo and the North County — well below the 104-degree reading in Paso Robles on Sunday.

A second cold front will arrive this weekend, with rain falling as far south as Monterey and snow dusting the high peaks in the Sierra Nevada mountains, Lindsey said.

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“A third cold front for the following week may produce the season’s first rainfall” for the county Oct. 7-9, Lindsey said.

He recalled that a year ago, light showers fell on the Harbor Festival in Morro Bay. That should not occur this weekend, when the annual event is scheduled, Lindsey said. But temperatures in Morro Bay will be in the low 60s, and skies will start out foggy.

Rain in October is not unusual — San Luis Obispo averages nearly an inch for the month. But November is when showers really start; the city’s average for the month historically jumps to 2.5 inches.

Drought buster?

Forecasters like Lindsey are hoping that the El Niño phenomenon can break the hold of a stubborn drought that has left the region with below-average rainfall the past three years and forced Paso Robles and Atascadero into mandatory water conservation programs.

During an El Niño, warm water from the central Pacific Ocean flows east toward South America and then north toward California.

Lindsey noted that on Monday morning the temperature of ocean water off Big Sur — measured by instruments on the Cape San Martin buoy — was 61.2 degrees. Normally the temperature there would be about 59 degrees. Even a few degrees of difference in ocean samples is significant.

“It is a good sign that we are seeing warmer-than-usual temperatures,” Lindsey said. “The El Niño may be strengthening. A weak El Niño does not have an effect at all, but moderate to strong El Niños seem to produce a greater amount of rainfall.”

Another sign of a strengthening El Niño is the current run of albacore tuna occurring off the California coast, delighting sports fishermen, Lindsey said.

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Snow on the mountains didn’t show up in SLO County, California, on Thursday, though frost was spotted in the Santa Margarita area. The weather forecast for the Central Coast shows rain next week into March.